1. Field Of The Invention
This invention relates to casement locks and more particularly to a casement lock for doors, French windows or the like, which comprises essentially a casing enclosing a mechanism for actuating a half-turn bolt and one or a plurality of operating rods provided with at least one locking member, a bolt for holding the operating rods in an inoperative position and release means fixed to the window frame and adapted, when closing the casing door or window, to engage the holding bolt and thus enable the resilient means to return the operating rods to their locking position.
2. The Prior Art
A casement lock having the above-mentioned features is already known in the art. Thus, this known casement lock comprises a casing enclosing a number of component elements of the mechanism controlling the movements of one or a plurality of operating rods and a half-turn bolt. As a rule, these operating rods are provided with one or a plurality of locking members or bolts engageable in keepers fixed to the frame or dormant of the door, French window or the like. Moreover, this casement lock comprises resilient means, notably in the form of spiral springs, constantly urging the operating rods to their locking position without requiring any actuation of the handle-bar. However, a primary requirement in casement locks of this type is that this return movement of the operating rods takes place only during the closing movement of the casement door or window.
For this purpose, the casement lock further comprises a locking member adapted to hold the operating rods in a release position. This locking member becomes operative when the handle-bar is turned to open the door, French window or the like. In contrast thereto,when closing the door or window, release means fixed to the door or window frame cooperate with this locking member to release the operating rods which are then returned instantaneously to their locking position by the abovementioned spiral spring.
It is also known in the art to use resilient means for returning automatically the operating rods of a casement bolt to their release position. Thus, to hold said rods in their release position the casement lock is provided with locking means comprising a stud projecting from the visible surface of the top rail. During the closing movement of the door or window, this stud is pushed inwards and releases the locking means. As a result, the operating rods are urged instantaneously to their locking position. In contrast to the first casement lock construction mentioned hereinabove, the operating rods in this prior arrangement are moved in opposite directions and the resilient means consist of coil compression springs.
By reason of the resilient means urging the operating rods, most hitherto known casement locks display an advantageous feature consisting in the quick response of the mechanism when locking a door, French window or the like. This feature is inasmuch advantageous in that the door or window is locked simultaneously at several points without requiring any intervention from the user. However, this type of casement lock is also attended by a number of far from negligible inconveniences.
In fact, when closing a door, French window or the like, the release means fixed to the dormant or frame cooperate with the locking member associated with the operating rods so as to release these rods. At the end of their stroke, these operating rods or their locking members abute a stop member, usually of metal, and this shock produces a noise of relatively high intensity. The magnitude of the noise caused by the casement lock during the closing movement of the door or window increases with the gradual aging of the mechanism. This noise may prove particularly unpleasant in certain circumstances, notably in the case of collective or appartment houses.